rev limits
Kaddie
06-26-2004, 11:10 PM
do most or all cars have rev limiters? meaning can you just floor it in first and not shift at redline without blowing the engine, or will the car limit the revs and keep harming the engine?
sracing
06-27-2004, 03:51 PM
do most or all cars have rev limiters? meaning can you just floor it in first and not shift at redline without blowing the engine, or will the car limit the revs and keep harming the engine?
Well, I think most all newer cars with later model stock ECM's do. But I wouldn't test it that way. :)
Prior to ECM's most all cars did NOT have any limitation like this. However, most would stop breathing well enough due to the induction system or valve float, before they "blew the engine".
Jim
SR Racing
Well, I think most all newer cars with later model stock ECM's do. But I wouldn't test it that way. :)
Prior to ECM's most all cars did NOT have any limitation like this. However, most would stop breathing well enough due to the induction system or valve float, before they "blew the engine".
Jim
SR Racing
Killermoped
07-29-2004, 01:54 AM
The rev limit is there to keep you from hitting 10k rpm. If you floor it in first and hit the rev limiter and keep it pegged there for 15 minutes something(like the rods) will give in. Shift at redline and you'll be good.
nissanfanatic
08-29-2004, 05:26 PM
You shift right after you make peak horsepower. The rev limiter will keep the engine from spinning beyond safe limits if say something in the driveline broke. Don't redline the engine. Usually its a fuel cut which leans the engine out(not good). Valve float will kill the engine as well.
bjdm151
09-20-2004, 09:12 AM
The purpose of the redline is to prevent the engine from over revving.
This will usually occur after the engineered power curve falls off so during normal driving and hard driving there is usully no reason to put it all the way to the rev limiter. It is also extremely unsafe to go up to the rev limit under a no load or low load condition like neutral as this will stretch connecting rods and float valves.
This will usually occur after the engineered power curve falls off so during normal driving and hard driving there is usully no reason to put it all the way to the rev limiter. It is also extremely unsafe to go up to the rev limit under a no load or low load condition like neutral as this will stretch connecting rods and float valves.
tricksaturnsc2
11-22-2004, 09:56 PM
Bouncing off the rev limiter while accelerating is ok, but not recommended, it's when you downshift into too low a gear that you bend all your valves etc
Zgringo
11-23-2004, 02:48 AM
do most or all cars have rev limiters? meaning can you just floor it in first and not shift at redline without blowing the engine, or will the car limit the revs and keep harming the engine?
I havent the foggest where some of these answers came from, but for a stock engine the rev limit is where the engine should not go beyond to prevent engine damage. Some are computer controled and other's are driver controled. Without a tach. your only guessing your rev limit, and if your car has it built in all the better.
My car was limited to 7,000 RPM, but after changing the cams and springs and a few other things, my new rev. limit is 9,200RPM. I lanch at 5,500RPM, shift at 8,500 RPM and do the lights at 9,000, at 144.7 in 10.160 seconds. I have a 200 RPM safe zone so I don't do any engine damage.
My other car uses the same engine but different internals and has a 11,500 rev limit. Different shift points and different speeds.
The difference of red line and rev limit is as follows. The mfg. engineers determine the point a engine is making the most power and that is the red line. The rev limit is where the engine well be damaged if you exceed this point.
When you build a engine, the cam mfg. or dyno tuner well tell you your red line, and the cam mfg. well tell you your rev limits, determined by the cam profile and springs.
I hope this has been sone help.
Albert
I havent the foggest where some of these answers came from, but for a stock engine the rev limit is where the engine should not go beyond to prevent engine damage. Some are computer controled and other's are driver controled. Without a tach. your only guessing your rev limit, and if your car has it built in all the better.
My car was limited to 7,000 RPM, but after changing the cams and springs and a few other things, my new rev. limit is 9,200RPM. I lanch at 5,500RPM, shift at 8,500 RPM and do the lights at 9,000, at 144.7 in 10.160 seconds. I have a 200 RPM safe zone so I don't do any engine damage.
My other car uses the same engine but different internals and has a 11,500 rev limit. Different shift points and different speeds.
The difference of red line and rev limit is as follows. The mfg. engineers determine the point a engine is making the most power and that is the red line. The rev limit is where the engine well be damaged if you exceed this point.
When you build a engine, the cam mfg. or dyno tuner well tell you your red line, and the cam mfg. well tell you your rev limits, determined by the cam profile and springs.
I hope this has been sone help.
Albert
fredjacksonsan
11-24-2004, 11:50 AM
Well said Gringo. Dang, 11.5 redline you must have some crazy high tech stuff in there.
You may not need to redline to get maximum performance. I had an 86 Mercury Capri 5.0L, stock. Redline was around 6K, but you could really feel the power dropping off just above 5200.
You could debate that leaving it in the lower gear with less power would give better acceleration than moving to the next gear with more power.
You may not need to redline to get maximum performance. I had an 86 Mercury Capri 5.0L, stock. Redline was around 6K, but you could really feel the power dropping off just above 5200.
You could debate that leaving it in the lower gear with less power would give better acceleration than moving to the next gear with more power.
tricksaturnsc2
11-24-2004, 10:46 PM
Well a car that comes w/ a 6k redline isn't the same as a car that comes w/ an 8200 redline, and a 1.8 isn't the same as a 5.0.To make any car faster, you have to emphasize the high end (hp not tq), to do that, aggressive cams extrude honing, ITB's etc, all the power is shifted higher. If the stock peak is at 8k rpms, modify it and it could be 9500.
Zgringo
11-25-2004, 11:31 PM
Well a car that comes w/ a 6k redline isn't the same as a car that comes w/ an 8200 redline,
No, I never knew that. Thanks for the info.
"and a 1.8 isn't the same as a 5.0."{QUOTE]
Holy shit I would never have though that. Glad you pointed that out to me.
[QUOTE]To make any car faster, you have to emphasize the high end (hp not tq),"[QUOTE]
Now this statement I have a problem with. I know if you have a 500HP engine with 2 ft.lbs. torque you won't have enough power to pull a limber prick out of a lard barrell.
[QUOTE] to do that, aggressive cams extrude honing, ITB's etc, all the power is shifted higher. If the stock peak is at 8k rpms, modify it and it could be 9500.
What if I don't want my power band shifted higher? What if I want my peak lower?
Different type racing, different gear ratio, different car weight, different engine mods. such as turbo'd, N/A nitrous, These are the things that need to be addressed in building a car.
Some of the guys here are really sharp and know what there talking about, cause they have paid their dues.
In closing I have a statement.
a volkswagon bug isn't the same as a semi truck.
.
No, I never knew that. Thanks for the info.
"and a 1.8 isn't the same as a 5.0."{QUOTE]
Holy shit I would never have though that. Glad you pointed that out to me.
[QUOTE]To make any car faster, you have to emphasize the high end (hp not tq),"[QUOTE]
Now this statement I have a problem with. I know if you have a 500HP engine with 2 ft.lbs. torque you won't have enough power to pull a limber prick out of a lard barrell.
[QUOTE] to do that, aggressive cams extrude honing, ITB's etc, all the power is shifted higher. If the stock peak is at 8k rpms, modify it and it could be 9500.
What if I don't want my power band shifted higher? What if I want my peak lower?
Different type racing, different gear ratio, different car weight, different engine mods. such as turbo'd, N/A nitrous, These are the things that need to be addressed in building a car.
Some of the guys here are really sharp and know what there talking about, cause they have paid their dues.
In closing I have a statement.
a volkswagon bug isn't the same as a semi truck.
.
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